The invention relates to a device for seaming a package, in which device there are clamping jaws for attaching an end piece of the package into the package.

For filling packages with food, automatic package forming and filling lines are used, in which the package is formed of a blank, filled for example with liquid- like food, and sealed. For the manufacture of such packages, cardboard is normally used, in which at least one side has been treated with materials designed for the seaming, the gas and liquid tightness as well as printing of the package material. In the selection, forming and filling of such packages, particularly the requirements of cleanliness are taken into account; in other words, the package must also be tight at the seams, and the aim is to minimize the access of foreign substances and micro-organisms into the package in connection with the filling.

The package formed of a cardboard blank by seaming, partly still open, is filled in a filling unit, which is aseptic or fulfils the sufficient requirements of cleanliness, with liquid-like food which may be milk, juice or any other flowable food. The liquid-like food can also be viscous substance, and it refers to all liquid materials that can be packed by pouring. The packaged food can also be solid, especially composed of particles, such as in the form of pieces, powder, grains or flakes. After such a package has been filled, the aim is to seal it tightly as soon as possible. In the filling line, successive packages on a conveyor stop under a nozzle which dispenses a predetermined liquid volume or a mass of solid substance into each package.

For example, a fibre-based plastic coated material, such as cardboard, is used as a packaging material. This kind of material is commonly called liquid package laminate. The seaming coating is to be selected so that it can be heat-sealed or sealed with some other method. In the case of food product the gas and liquid tightness of the packaging material is important, and in addition to the sealable layer, there can be also one or more layers acting as a particular barrier. The packaging, for which the device for seaming a package according to the invention is intended to, comprises a tube-like shell part manufactured, for example, of cardboard blank by wrapping and sealing the edges to each other, wherein the edges overlap partly and attach to each other by means of a seaming coating of the cardboard, for example plastic coating, that is heated or otherwise energy treated to bring it to a sealing state. Of this shell part a closed package is made by attaching end pieces, whose outline corresponds to the cross-section of the shell, to both ends of the shell, which end pieces have been separated from the cardboard material for example by die cutting. The end pieces are sealed to the cylindrical part by pressing and exerting energy to the coating, which brings it into a sealing state. The material of the liquid package can also be other than a cardboard-based material.

In seaming the end piece it is particularly important to acquire an pressure for the circumference of the whole package, because otherwise weak spots, which degrade the preservability of the package, might remain in the joint. The mobile clamping jaws of the seaming device press the flange of the end piece from the middle towards the inside surface of the shell part and the counterpart outside the shell part. There are several mobile clamping jaws sector by sector on the periphery of the end piece, wherein areas remain between them where the pressure action is weaker. In order to reach an uniform thickness of the seam along the whole periphery of the end piece, two consecutive seaming devices are used in such a manner that the clamping jaws of the latter seaming device are in a different angular position and their centre hits the areas where the boundaries of the mobile clamping jaws of previous seaming device have located.

However, this arrangement does not take into account the uneven pressure due to the other structure of the package. The axial vertical seam of the shell part formed by edges seamed on top of each other cause a some kind of point of discontinuity in the joint of the end piece and the shell part, wherein the layer thickness is greater by one layer of the liquid package laminate.

Although the thickness of the liquid package laminate is usually under 1mm, and the material is somewhat compressible under pressure, however, a short area is formed immediately on both sides of the vertical seam in the direction of the periphery of the end piece, in which area it can be presumed that the material of the end piece and the material of the shell part do not press at the same force against each other than in the areas further away of the vertical seam. This is at least a clear factor of uncertainty in the impermeability of liquid packages where seams are precisely the most critical points.

It is the aim of the invention to eliminate the aforementioned drawbacks and to present a device for seaming a liquid package, which can be used to create an even more secure seam for the whole periphery of the end piece. To attain this purpose, the seaming device according to the invention is primarily characterized in that in a fixed counterpart of the seaming device there is a zone made of elastic material opposite to the press surface of the mobile clamping jaw, which zone is at least partly capable of yielding to the extra layer of packaging material between the mobile clamping jaw and the fixed counterpart.

The elastic material of the zone, which can be of suitably hard rubber or elastomer, is capable of adapting to the extra thickness caused by the vertical seam, as a result of which the vertical seam sinks into the elastic material at the height of the mobile clamping jaw at least partly by the thickness of the extra layer, i.e. by the thickness of the topmost blank edge of the vertical seam.

As material for the shell part and the end piece, a liquid package laminate can be used, which material has suitable properties for the packaged liquid food and is cardboard or packaging material based on some other material, which comprises the layer of the seaming material at least on the surface to be fixed seaming. The liquid package laminate can have one or several plastic layers acting as barriers or one aluminium layer acting as a barrier.

In the following, the invention will be described in more detail with reference to the appended drawings, in which

Fig. 1 shows schematically the phase preceding the seaming device, wherein liquid is packaged in cycles, Fig. 2 shows a vertical cross-section of a detail of the seaming device,

Fig. 3 shows a horizontal section of the operation of the seaming device at the location of the vertical seam before the pressing, and

Fig. 4 shows a horizontal section of the operation of the seaming device during the pressing phase at the location of Fig. 3.

In Fig. 1 the operation of the filling device preceding the seaming device in the filling line is shown to illustrate the use of the invention. The filling device comprises a product container 1 , into which liquid food or solid food (as particles such as pieces, powder, grains or flakes) is supplied by a feeding channel 2. In the figure, a feeding channel 2 is introduced in the lower part of the container 1 from the side near the bottom of the container (solid lines), but it can also be introduced from below to the bottom of the container, or from above to the container (broken lines). From the bottom of the product container, a filling channel 3 extends downwards, its lower end being provided with a filling valve 4 to open and close the filling channel for filling bypassing liquid packages P, transferred on a conveyor, with a predetermined liquid volume or mass of solid material. From the product container, the liquid or solid material flows into the channel 3 and into the package P by gravity or additionally by the effect of pressure in the container. After the filling phase the packages are moved to the closing phase, which is illustrated with an arrow S in Fig. 1.

The liquid packages are normally made by seaming a liquid packaging laminate. The packages can be different in shape, and the shell parts have been manufactured, for example, of cardboard blanks by wrapping and seaming the edges together. The package is sealed by attaching end pieces separated from cardboard material for example by die cutting to the both ends of the shell part, which pieces are seamed to the shell part. The shell part can be cylindrical, but the cross-section of the package can be other than round, and it is characteristic for all these kinds of packages to have a tube-like shell part formed of a blank by wrapping and closed at both ends. According to one alternative, steps are taken so that the end piece forming the lid in the finished package, where there is a drinking aperture sealed with a suitable manner, is seamed to the end of the shell part already in the package forming unit, and the container-like package, whose other end is still open, is transferred to the filling and sealing unit, where it moves in an upright position with the open end facing upwards first under the filling device in Fig. 1 and then under the sealing device on a conveyor that transfers the packages successively to the filling phase and sealing phase step by step. In the sealing phase S an end piece forming the bottom of the package is placed at the open end, which piece is sealed to the upper edge of the above-mentioned shell part. Principles for forming and sealing the package have been disclosed e.g. in an earlier patent publication EP 1091874 B1. However, it is possible that the end piece to be placed in the package after the filling phase S is the lid of the finished package, and the end piece forming the bottom of the package has been installed previously in the package forming unit.

The function of the seaming device of the sealing device is shown as a vertical view in the height direction of the package in Fig. 2. The end piece E sealing the end of the package P, which is also, for example, of coated, fiber- based material such as cardboard, is inserted with a gripper known as such from the top inside the shell part of the package P to a suitable distance from the upper surface of the liquid N so that the edge flange E1 turned upwards of the end piece E stays against the inner wall of the shell part. There is a material sealable by means of heat or other energy brought from outside, such as heat-sealable plastic, on the lower surface of the end piece E and in the inner wall of the shell part.

When the end piece is in its place, the package P is lifted up to the seaming device 5 having clamping jaws 6 that clamp the edge flange E1 and the upper edge of the shell part between the mobile jaws and the fixed counterpart 7 of the seaming device. The fixed counterpart 7 of the seaming device acts, in a way, as a counterpart for the pressing and surrounds in an annular manner the upper edge of the shell part from the outside, and radially outward mobile jaws 6, which are several, situated in different sectors, press with their press surfaces 6a corresponding to the shape of the edge flange of the end piece from the centre against the upper edge of the shell part and the fixed counterpart 7. If the of cross-section of the shell part and the end piece are circular in their shape or have a different shape, the mobile jaws 6 are segments shaped like an arc or the outline of the different shape. The mobile jaws 6 can be heated or they can have means, which exert energy to the opposite coating materials and cause the seaming of these to each other. The mobile jaws 6 and the fixed counterpart 7 (counterpiece) are above the conveyor moving filled packages P step by step. When the package P has moved under the seaming device, it is lifted with an actuator up to the seaming device in such a manner that the edge flange E1 of the end piece and the upper edge of the shell part come between the annular or differently shaped space of the clamping jaws 6 and the fixed counterpart 7.

There is a zone of elastic material 7a in the fixed counterpart 7 at the location of the press surface 6a of the mobile clamping jaw in the height direction, which zone surrounds the upper edge of the shell part of the package in an annular manner at the height of the seaming location. The clamping pressure caused by the press surface 6a affects precisely their zone 7a. The zone of the elastic material 7a is located in the inner surface of ring piece 7b inserted from the top to the frame of the fixed counterpart 7. The ring piece can be replaced, if it is desired for example to change an elastic material of different hardness in the seaming device, or even to change a ring piece 7b which does not have elastic material, wherein its function corresponds to a normal hard-surfaced counterpiece.

The elastic zone 7a can be attached directly to the frame of the counterpart 7 without a ring piece. It can be attached permanently by means of vulcanization or adhesively or made replaceable in a groove of the counterpart.

The zone 7a can consist of a ring made of elastic material, which is located in a recess in the inner surface of the ring piece 7b. The elastic material is of rubber or elastomer which has a suitable hardness, clearly more elastic than the counterpart 7 and its possible ring piece 7b that are made of metal. The hardness of the elastic material, based on tests, is 65 to 75 shore for normal liquid package laminate. The ring piece 7b shown in Fig. 2 is a piece to be placed from the top between the frame of the counterpart 7 and the clamping jaw, which piece remains in its place by a means of a collar extending outwards in the upper part of the piece. The collar rests against the upper surface of the frame of the counterpart 7. At the lower end of the piece 7b there is a conical guiding surface meant for the upper end of the package P. If necessary, the ring piece can be replaced with a replacement piece of a same shape, in which piece a hard surface is in the place of the elastic material, i.e. the whole replacement piece can be of the same material. The use of the replacement piece is advantageous if the same seaming device is used for seaming different types of package material.

As it is stated in an illustrative way in the Fig. 3 and 4, the function of the seaming device in the location where the vertical seam P1 of the shell part of the package (the edges of the blank of the shell part on top of each other) falls on the range of action of the mobile clamping jaw 6 of the seaming device. The triple layer thickness caused by the edge flange E1 and the vertical seam P1 together, which would cause an uneven pressing action between the hard press surfaces in the areas of double thickness immediately on both sides of the vertical seam, in a away, is absorbed to the zone 7a of the elastic material precisely at the location of the vertical seam P1. Otherwise, the elastic material does not cause problems to the pressing force because the material is homogenous and sufficiently hard on the whole periphery of the counterpart 7, and the material yields suitably precisely at the location of the vertical seam. The vertical seam P1 sinks into the elastic material at the height of the mobile clamping jaw at least partly by the thickness of the extra layer, i.e. the thickness of the topmost blank edge of the vertical seam. The topmost blank edge of the vertical seam P1 also slightly bends to the level of the lower blank edge at a location where the lower blank edge ends, in such a manner that the seam immediately on both sides of the vertical seam approaches a situation wherein there are two cardboard layers between the clamping jaws 6 and the fixed counterpart 7.

To make the seaming evenly strong over the whole periphery of the shell part, the package P is transferred maintaining its position with the conveyor to another seaming device where the mobile jaws 6 are in different angular position in relation to the previous seaming device. The jaws 6 and the fixed counterpart 7 compress and seam the edge flange and the shell part in locations that remained between the range of actions of the jaws 6 of the previous seaming device and where the joint can be weaker. This latter seaming device also has the structure described above.

When the edge flanges E1 and the upper edge of the shell part have been sealed together, short section of the upper edge of the shell part remained above the upper end of the edge flange is turned over the edge part. This can be performed in a particular finishing seaming unit, the purpose of which is to primarily achieve a clean, finished appearance to the closed package.

The invention is not restricted to the embodiments described above, but it can be modified within the scope of the inventive idea presented in the claims. As mentioned above, the invention is not depended on the position of the sealed end piece in the final liquid package sold to the consumer. The position of the vertical seam of the packages coming to the conveyor of the filling line is not predictable, for which reason it is advantageous to use a zone of elastic material extending to the whole periphery. If the position of the vertical seam is predictable in such a manner that with certainty it always falls within an area of a given length in the direction of the periphery of the fixed counterpart 7, the fixed counterpart needs to be equipped with a zone of elastic material 7a only over the length of this area. The ring piece, where the elastic material is, or its replacement piece, which has a hard surface, can also be replaced with an arc-shaped piece of corresponding length.

Moreover, the invention is not limited to the seaming devices in the filling line but it can be used in seaming devices, which in the package forming unit with a corresponding principle seal the first end piece to the shell part for manufacturing a container going to the filling line, if the manufacturing method is such that the position of the vertical seam is not precisely predictable and it cannot be otherwise taken into account in the structure of the seaming device. Thus, the seaming device of the liquid package is either the seaming device for a package filled with food product or a seaming device for a not yet filled package.